1. Technical Field
The present invention relates to a computer system with mode switching functions, and more particularly, relates to a computer system capable of supporting a variety of communication services in response to a mode selection signal over a communication line, and a method of controlling the same.
2. Related Art
Generally, local and remote computers communicate over a telephone line by way of computer modems. Conventional computer terminals can support a variety of communication services, such as data, facsimile, and voice through the modem mounted thereto. Computer modem is an interface device coupled to the computer terminal and a telephone line to permit the exchange of digital data with remote modem-supported computer terminal over the telephone line. Some computer modems as disclosed, for example, in U.S. Pat. No. 5,059,141 for Modem/Telephone Handset Cord Adaptor issued to Scott, U.S. Pat. No. 5,249,218 for Programmable Universal Interface System and U.S. Pat. No. 5,367,563 for Programmable Universal Modem System And Method For Using The Same both issued to Sainton, are selectively operated using communications software to support communication with a variety of different telephone systems.
Computer modem is typically plugged into a telephone jack connected to a telephone line and is positioned inside or adjacent to the computer terminal. To support data transmission to a remote computer terminal, the modem transforms the digital data from the local computer terminal into analog format necessary for telephone line transmission. At the receiving end, a second modem of the remote computer terminal transforms received analog signal into digital data which is provided to its local computer terminal. While the conventional computer modems are configured to communicate in facsimile communication mode, there is no standardized configuration for modems to process in two or more data communication modes including data, facsimile and voice. This is because the modems cannot discriminate a dual tone multi-frequency (DTMF) code signal following a ring signal. As a result, conventional computer systems cannot support a variety of communication services in response to the DTMF code signal serving as a communication mode.
One recent effort to configure computer modems to support a variety of communication services including data, facsimile and voice is disclosed in U.S. Pat. No. 5,361,296 for Modem With Ring Detection/Modem Processing Circuitry issued to Reyes et al. However, the modem processing circuitry of Reyes '296 requires a facsimile/data modem software with data protocol that responds to distinctive ring type associated with a ring signal offered by telephone companies. The modem of Reyes '296 does not discriminate the DTMF signal following the ring signal to support the communication services. While the computer modem of Reyes '296 has its own merits, I have observed that further improvement can still be contemplated.